High-Throughput Continuous-Flow Ultrasound Reactor

ABSTRACT

Liquids are treated by ultrasound in a flow-through reaction vessel with an elongate ultrasonic horn mounted to the vessel with one end of the horn extending into the vessel interior. The liquid flow path inside the vessel is such that the entering liquid strikes the end of the horn at a direction normal to the end, then flows across the surface of the end before leaving the vessel. The end surface of the horn is positioned in close proximity to the entry port to provide a relatively high surface-to-volume ratio in the immediate vicinity of the horn end. In a further improvement, the horn is joined to an ultrasonic transducer through a booster block that provides an acoustic gain to the ultrasonic vibrations, and the booster block is plated with a reflective metal to lessen any loss of ultrasonic energy being transmitted to the horn.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention resides in the field of process equipment used in thetreatment of materials in liquid media by ultrasound, and also in theprocessing of petroleum and petroleum-based fuels.

2. Description of the Prior Art

The use of ultrasound for driving chemical reactions is well known.Descriptions are found in Suslick, K. S., Science 247:1439 (1990), andMason, T. J., Practical Sonochemistry, A User's Guide to Applications inChemistry and Chemical Engineering, Ellis Norwood Publishers, WestSussex, England (1991). A variety of ultrasound systems have beendescribed, and among the most prominent are “probe”-type systems, whichinclude an ultrasonic transducer that generates ultrasonic energy andtransmits that energy to a probe, i.e., an ultrasonic horn, foramplification.

Uses of ultrasound have recently been extended to include petroleumprocessing, notably for the desulfurization of fossil fuels and theconversion of high molecular weight components of petroleum to lowermolecular weight products, thereby improving the conversion of crudeoil, and particularly of crude oil resids, to useful materials.Disclosures of these processes and the equipment in which they areperformed are found in Yen, T. F., et al., U.S. Pat. No. 6,402,939,issued Jun. 11, 2002, Gunnerman, R. W., U.S. Pat. No. 6,500,219, issuedDec. 31, 2002, Gunnerman, R. W., U.S. Pat. No. 6,652,992, issued Nov.25, 2003, Gunnerman, R. W., et al., United States Pre-Grant PatentApplication Publication No. US 2003-0051988 A1, published Mar. 20, 2003,Gunnerman, R. W., United States Pre-Grant Patent Application PublicationNo.

US 2004-0079680 A1, published Apr. 29, 2004, Gunnerman, R. W., et al.,U.S. patent application Ser. No. 10/440,445, filed May 16, 2003, andGunnerman, R. W., et al., U.S. patent application Ser. No. 10/803,802,filed Mar. 17, 2004. The contents of each of the documents cited in thisparagraph and elsewhere throughout this specification are herebyincorporated herein by reference in their entirety for all legalpurposes capable of being served thereby.

Ultrasound processing offers a vast potential for the petroleumindustry, but its value is highly sensitive to processing costs, andparticularly the energy consumption involved in generating theultrasonic vibrations. The present invention offers improvements inultrasound processing equipment that provide a more efficient use ofenergy, enabling the processing of particularly large quantities ofmaterial in a highly economic manner.

SUMMARY OF THE INVENTION

It has now been discovered that ultrasound treatment can be applied to afluid material on a continuous-flow basis with a highly efficient use ofenergy by incorporating certain structural improvements in the reactionvessel and the ultrasound components.

In one of these improvements, a reaction vessel is constructed with anelongate ultrasonic horn mounted to the vessel such that one end of thehorn extends into the vessel interior, with a power source and anultrasonic transducer operatively connected to an opposing end of thehorn. Upon its entry into the vessel, the fluid material directlystrikes the distal end of the horn, i.e., the end opposite the end towhich the power source and transducer are connected, at a directionsubstantially normal to the distal end, then flows over the surface ofthe distal end before leaving the vessel through one or more exit portsin the vessel wall. The portion of the reaction vessel interior that theflowing fluid occupies as it contacts the distal end of the ultrasonichorn is restricted by placing the distal end close to the entry port,with a relatively high surface-to-volume ratio, referring to the distalend surface and the portion of the vessel volume that the fluid flowsthrough while in contact with the distal end.

In a further improvement, the ultrasonic vibrations are produced by anelectrical power source and an ultrasonic transducer, the transducerjoined to the horn through a vibration transmitting block or booster,and either the block, the horn, or both are clad with a material thatreflects the ultrasonic vibrations. The cladding retains vibrationalenergy within the block that would otherwise escape from lateralsurfaces of the block that are not operatively connected to the horn.This reduction of energy loss through the lateral surfaces of the blockcauses a greater proportion of the vibrational energy from thetransducer to be transmitted to the horn.

Further improvements, features, and embodiments of the invention will beapparent from the description that follows.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is an axial cross section of an ultrasound reactor in accordancewith the present invention.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS

While this invention is susceptible to a variety of implementations andconfigurations, a detailed study of a specific system within the scopeof the invention will provide the reader with a full understanding ofthe concepts of the invention as a whole and how they can be applied.One such system is shown in the Figure.

FIG. 1 is an axial cross section of a continuous-flow reactor 11 inwhich a flowing reaction medium is exposed to ultrasound in accordancewith this invention. The reactor consists of a reaction chamber 12 withan entry port 13 for the inflow of the reaction medium and exit ports,of which two 14, 15 are shown, through which the treated reaction mediumleaves the chamber. Mounted to the reactor is an ultrasonic horn 16whose distal end 17 extends into the interior of the reaction chamber12. The proximal end 18 of the horn is joined by way of a coupling stud19 to a connecting block 21 that in turn is joined to an ultrasonictransducer 22. The connecting block serves as vibration transmitter fromthe transducer to the horn 16, and as a waveguide and booster toincrease the amplitude of the ultrasonic vibrations that are produced bythe transducer 22. The transducer 22 is joined to an electrical powerunit 23 which includes a power source, an amplifier, and a controller.

For best results, the material to be treated follows a flow path thatsweeps across the surface of the distal end 17 of the ultrasonic horn,preferably the entire surface, with a continuous, constant flow andlittle or no dead volume. In the configuration shown in FIG. 1, this isachieved by using an ultrasonic horn with a flat (planar) distal end 17and arranging the entry port 13 to direct the incoming flow to thecenter of the distal end surface, from which the flow proceeds radiallyoutward to the peripheral rim 24 of the distal end and leaves thereaction chamber after having passed over the peripheral rim 24. Thehorn 16 is thus preferably cylindrical in shape with a circular distalend 17, and although the dimensions can vary within the scope of thisinvention, the distal end will preferably range in diameter from about 3cm to about 30 cm, more preferably from about 5 cm to about 15 cm. Thegap 25 between the floor 26 of the reaction chamber through which theincoming fluid enters and the distal end 17 of the horn can likewisevary, although for best results in most applications, the gap width isless than 3.0 cm, preferably less than 2.0 cm, and most preferably lessthan 1.5 cm. Preferably, the minimum gap width is 0.5 cm, and mostpreferably 1.0 cm. The surface-to-volume ratio, as defined above, ispreferably about 0.5 cm⁻¹ or above and most preferably ranges from about0.5 cm⁻¹ to about 5 cm⁻¹. In a presently preferred embodiment, thedistal end is about 3.0 inches (7.6 cm) in diameter, and the gap isabout 0.5 inch (1.3 cm).

To minimize the amount of dead volume in the reaction chamber 12, thechamber preferably encloses only the distal end 17 of the ultrasonichorn 16 and a portion of the length of the horn adjacent to the distalend, as shown in the Figure. The upper end of the chamber is thus closedoff by a barrier 28 that is sealed around the sides of the horn. Inaddition, the reaction chamber 12 has an internal wall surface 31 thatis complementary in shape to the portion of the ultrasonic horn 16 thatextends into the chamber interior, with only a narrow lateral gap orclearance 32, and the exit ports 14, 15 are positioned only a smalldistance beyond the distal end 17 of the horn. In preferredconstructions, this clearance 32 is less than 2.0 cm in width, morepreferably less than 1.5 cm in width, and most preferably less than 1.0cm in width.

While the ultrasonic transducer 22 is described in detail below, thetransducer and the adjacent portion 33 of the connecting block 21 aresurrounded by a cooling chamber 34 to limit the temperature riseresulting from the vibrations in the transducer and block. A flange 35encircling the block serves as the floor of the cooling chamber. Whilethe various components of system, including the reaction chamber 12, theultrasonic horn 16, the connecting block 21, and the coolant chamber 34are not limited to any particular shape, they are most conveniently andeconomically formed as bodies of revolution about a common axis 36.

The ultrasonic horn 16 in particular can be of any conventional shapeand size that may be known in the prior art for ultrasonic horns. Thehorn may for example be cylindrical, preferably of circular crosssection as indicated above, and suitable lengths may range from about 5cm to about 100 cm, depending on the reactor size, and preferably fromabout 10 cm to about 50 cm, with a diameter of from about 3 cm to about30 cm, and preferably from about 5 cm to about 15 cm. The block 21,which serves as both a mechanical connection that transmits theultrasound vibrations from the transducer to the horn and an amplifierof the ultrasound waves by virtue of its tapering profile can likewisevary in its dimensions. With a block of the shape shown, a suitablelength range is about 5 cm to about 100 cm, and most preferably fromabout 10 cm to about 50 cm, with its widest diameter preferably rangingfrom about 3 cm to about 30 cm, and preferably from about 5 cm to about15 cm.

In preferred embodiments, the length of the block 21 is one-half thewavelength of the resonating frequency of the block. Furthermore, tominimize acoustical energy losses to the walls of the structure throughthe flange 35, the mounting fixture 37 on the block is positioned alongthe axis of the block at a distance equal to one-fourth the resonatingfrequency and thus the midpoint of the axial length of the block. Asnoted above, the block is preferably tapered as shown to provide a gainin acoustical amplitude from the transducer end to the end at which thehorn 16 is mounted. This taper reduces the block diameter in thedirection of the horn.

In a presently preferred construction, the horn 16 is about 13 cm inlength and about 8 cm in diameter, and the block 21 is about 6 cm inlength, about 8 cm in width in its widest portion, and about 5 cm inwidth at its narrower portion.

Metals from which the horn 16 and the block 21 can be made are wellknown in the art of ultrasound. Examples are steel, including stainlesssteel, tool steel, and other steels, as well as nickel, aluminum,titanium, copper, and various alloys of these metals. The block 21 ispreferably made of steel, and the horn 16 is preferably made of aluminumor titanium. In a presently preferred construction, the block 21 is madeof A2 tool steel and the horn 16 is made of aluminum.

The horn 16 or the block 21 or both can be clad with an ultrasoundreflecting cladding to further reduce energy losses. In preferredembodiments of the invention, the block 21 is clad, with or withoutcladding of the horn 16 as well. Examples of materials that will serveas the ultrasound reflecting cladding are silver, gold, copper andaluminum. While certain metals are listed herein as suitable for boththe body of the horn or block and the cladding, the metals serving asthe body and the cladding will be different metals. Preferred among themetals for the cladding are silver and gold, with silver the mostpreferred. The cladding can be applied by any conventional method, ofwhich electroplating and electroless plating are two examples.

The ultrasonic transducer can be of the configuration described inGunnerman, R. W., et al., U.S. patent application Ser. No. 10/440,445,referenced above. To reiterate the description in that document, thetransducer contains a stack of plates of a magnetic alloy that operatesas a magnetostrictive material. The stack forms a pair of prongs thatare wound with coils of electrical wire. The prongs can be joined bycrossbars at both ends to form a closed loop. Each plate can thus be arectangular plate with a central elongated opening. Any soft magneticalloy is suitable for use as the plate material. Examples areiron-silicon alloys, iron-silicon-aluminum alloys, nickel-iron alloys,and iron-cobalt alloys, many of these containing additional alloyingelements such as chromium, vanadium, and molybdenum. Examples ofcommercially available forms of these alloys are those sold under thetrade names HIPERCO® 27, HIPERCO® 35, 2V PERMENDUR®, and SUPERMENDUR. Apresently preferred alloy is HIPERCO® Alloy 50A (High Temp Metals, Inc.,Sylmar, Calif., USA).

In a presently preferred method of fabricating the prongs, individualplates are cut from a sheet of the raw magnetic alloy material that is0.017 inch (0.0067 cm) in thickness. Each plate is cut to a length equalto one-half the wavelength of the desired resonating frequency. Thus,for a resonating frequency of 17.5 kHz, for example, the preferredlength of each plate is 5.125 inch (13.0 cm). The central elongatedopening is cut large enough to permit the passage of electrical wire toform the coils on each side of the opening. In the preferredconstruction, the remaining portions of the plates around which thecoils are wound are 3.6 inch (9.1 cm) in length and 0.83 inch (2.1 cm)in width, the opening being 0.73 inch (1.9 cm) in width.

The plates can be heat treated to maximize their performance ascomponents of an ultrasound transducer. In a presently preferred methodof treatment, the plates are heated in an inert atmosphere at a rate of1,000 deg F./hour (556 deg C./hour) to 900° F. (482° C.), then at 400deg F./hour (222) to 1,625° F. (885° C.), then soaked at thistemperature for several hours (approximately three hours, 45 minutes),then cooled at 3.2 deg F./hour (1.7 deg C./hour) to 600° F. (316), andfinally to room temperature. The plates are then bonded together to forma stack, which can contain as many as 96 plates. Once bonded, the platestack is joined to the block by brazing with a silver brazing material.

The plate stack is then wound with electrical wire to form the coils andthereby complete the formation of the transducer. Separate coils areformed around each of the two prongs, in opposite directions so thatwhen a voltage is applied across both windings the magnetic polaritiesarising from the resulting current are in opposite directions andmagnetostrictive forces are created in a direction parallel to the axesof the prongs. For the specific construction referenced above, asuitable wire is 14 AWG MIL SPEC Wire, and the coil contains 32 turns.

The transducer can be powered by any oscillating voltage. Theoscillations can be a continuous waveform oscillation such as sinusoidalwave or a series of pulses such as rectangular waveform pulses. By“rectangular waveform” is meant a direct current voltage that alternatesthrough stepwise voltage changes between a constant positive value and abaseline value. Rectangular waveforms that are preferred in the practiceof this invention are those in which the baseline is a negative voltagerather than a zero voltage, and preferably those in which thealternating positive and negative voltages are of the same magnitude.Preferred voltage is from about 140 volts to about 300 volts, andpreferably about 220 volts single-phase, and the preferred wattage isfrom about 1 kilowatt to about 10 kilowatts. The frequency of thevoltage oscillation will be selected to achieve the desired ultrasoundfrequency. Preferred frequencies are in the range of about 10 to about50 megahertz, with a range of about 15 to about 30 megahertz mostpreferred.

Aside from the particular ultrasound transducer described above anddepicted in FIG. 1, ultrasonic vibrations in the horn 16 can be producedby a variety of methods known among those skilled in the use ofultrasound. Ultrasound consists of soundlike waves at a frequency abovethe range of normal human hearing, i.e., above 20 kHz (20,000 cycles persecond). Ultrasonic energy has been generated with frequencies as highas 10 gigahertz (10,000,000,000 cycles per second), but for the purposesof this invention, useful results will be achieved with frequencieswithin the range of from about 30 kHz to about 300 MHz, and preferablywithin the range of from about 1 MHz to about 100 MHz. Ultrasonic wavescan be generated from mechanical, electrical, electromagnetic, orthermal energy sources. While the intensity of the energy can varywidely, best results will generally be achieved with an intensityranging from about 30 watts/cm² to about 300 watts/cm², or preferablyfrom about 50 watts/cm² to about 100 watts/cm². An alternative to themagnetostrictive transducer as described above is a piezoelectrictransducer, which uses natural or synthetic single crystals (such asquartz) or ceramics (such as barium titanate or lead zirconate) andapplies an alternating electrical voltage across opposite faces of thecrystal or ceramic to cause an alternating expansion and contraction ofcrystal or ceramic at the impressed frequency. Other methods known inthe art can be used as well.

Any liquid reaction medium that will benefit from treatment byultrasound can be processed in the reactor and by the methods of thisinvention. A reaction medium of particular interest is liquid fossilfuels, which term is used herein to denote any carbonaceous liquid thatis derived from petroleum, coal, or any other naturally occurringmaterial and that is used to generate energy for any kind of use,including industrial, agricultural, commercial, governmental, andconsumer uses. Included among these fuels are automotive fuels such asgasoline, diesel fuel, jet fuel, and rocket fuel, and petroleumresiduum-based fuel oils such as bunker fuels and residual fuels.Examples of bunker fuels are Nos. 4, 5, and 6 fuel oils, the latter alsoknown as “Bunker C” fuel oil. The invention is also applicable topetroleum resids including vacuum resid, i.e., the heaviest fuel oilfrom the fractional distillation of petroleum, with a boiling point of565° C. and above.

When the reaction medium is an oil, and particularly a fossil fuel,ultrasound in accordance with this invention is applied to an emulsionof the oil in an aqueous phase. Water or any aqueous solution can serveas the aqueous phase. The relative amounts of organic and aqueous phasesmay vary, and while the proportion may affect the efficiency of theprocess or the ease of handling the fluids, the relative amounts are notcritical to this invention. In most cases, however, best results will beachieved when the aqueous phase constitutes from about 20% to about 75%of the emulsion, preferably from about 30% to about 50%.

A hydroperoxide can be included in the emulsion as an additive, but isnot critical to the success of the conversion. The amount ofhydroperoxide when present can vary. In most cases, best results will beachieved with a hydroperoxide concentration of from about 10 ppm toabout 100 ppm by weight, and preferably from about 15 ppm to about 50ppm by weight, of the aqueous phase, particularly when the hydroperoxideis H₂O₂. Alternatively, when the H₂O₂ amount is calculated as acomponent of the combined organic and aqueous phases, best results willgenerally be achieved in most systems with an H₂O₂ concentration withinthe range of from about 0.0003% to about 0.03% by volume (as H₂O₂), andpreferably from about 0.001% to about 0.01%, of the combined phases. Forhydroperoxides other than H₂O₂, the preferred concentrations will bethose of equivalent molar amounts.

In certain embodiments of this invention, a surface active agent orother emulsion stabilizer is included to stabilize the emulsion as theorganic and aqueous phases are being prepared for the ultrasoundexposure. Certain petroleum fractions contain surface active agents asnaturally-occurring components of the fractions, and these agents maybesufficient to stabilize the emulsion. In other cases, synthetic surfaceactive agents or those that are not native to the petroleum can beadded. Any of the wide variety of known materials that are effective asemulsion stabilizers can be used. These materials are listed in variousreferences such as McCutcheon's Volume 1: Emulsifiers & Detergents—1999North American Edition, McCutcheon's Division, MC Publishing Co., GlenRock, N.J., USA, and other published literature. Cationic, anionic andnonionic surfactants can be used. Preferred cationic species arequaternary ammonium salts, quaternary phosphonium salts and crownethers. Examples of quaternary ammonium salts are tetrabutyl ammoniumbromide, tetrabutyl ammonium hydrogen sulfate, tributylmethyl ammoniumchloride, benzyltrimethyl ammonium chloride, benzyltriethyl ammoniumchloride, methyltricaprylyl ammonium chloride, dodecyltrimethyl ammoniumbromide, tetraoctyl ammonium bromide, cetyltrimethyl ammonium chloride,and trimethyloctadecyl ammonium hydroxide. Quaternary ammonium halidesare useful in many systems, and the most preferred are dodecyltrimethylammonium bromide and tetraoctyl ammonium bromide.

Surface active agents of particular interest are those that will promotethe formation of an emulsion between the organic and aqueous phases uponpassing the liquids through a common mixing pump, and yet allow theproduct mixture to separate spontaneously and readily into aqueous andorganic phases upon leaving the reactor. Once settled, the phases can beseparated by decantation or other conventional phase separationtechniques. One class of surface active agents that will easily form anemulsion and yet separate readily upon leaving the reactor is liquidaliphatic C₁₅-C₂₀ hydrocarbons and mixtures of such hydrocarbons,preferably those having a specific gravity of at least about 0.82, andmost preferably at least about 0.85. Examples of hydrocarbon mixturesthat meet this description and are particularly convenient for use andreadily available are mineral oils, preferably heavy or extra heavymineral oil. These oils are readily available from commercial chemicalssuppliers. The amount of mineral oil can vary and the optimal amount maydepend on the grade of mineral oil, the composition of the material tobe treated, the relative amounts of the aqueous and organic phases, andthe operating conditions. Appropriate selection will be a matter ofroutine choice and adjustment by the skilled engineer. In the case ofmineral oil, best and most efficient results will generally be obtainedwhen the volume ratio of mineral oil to the organic phase is from about0.00003 to about 0.003.

Another additive that is useful in forming and stabilizing the emulsionis a dialkyl ether. Preferred dialkyl ethers are those having a normalboiling point of at least 25° C. or whose molecular weight is at mostabout 100. Both cyclic and acyclic ethers can be used. Examples ofpreferred dialkyl ethers in the practice of this invention are diethylether, methyl tertiary-butyl ether, methyl-n-propyl ether, and methylisopropyl ether. The most preferred is diethyl ether. The amount of thedialkyl ether can vary, although in most cases best results will beobtained when the volume ratio of ether to the oil phase is from about0.00003 to about 0.003, and preferably from about 0.0001 to about 0.001.

Another optional component of the system is a metallic catalyst.Examples are transition metal catalysts, preferably metals having atomicnumbers of 21 through 29, 39 through 47, and 57 through 79. Particularlypreferred metals from this group are nickel, silver, tungsten (andtungstates), and combinations thereof. In certain systems within thescope of this invention, Fenton catalysts (ferrous salts) and metal ioncatalysts in general such as iron (II), iron (III), copper (I), copper(II), chromium (III), chromium (VI), molybdenum, tungsten, and vanadiumions, are useful. Of these, iron (II), iron (III), copper (II), andtungsten catalysts are preferred. Tungstates include tungstic acid,substituted tungstic acids such as phosphotungstic acid, and metaltungstates. The metallic catalyst may be present as metal particles,pellets, screens, or any form that has high surface area and can beretained in the ultrasound chamber.

Further improvement in the efficiency of the process is often achievableby preheating the organic phase, the aqueous fluid, or both, prior toforming the emulsion or to exposing the emulsion to ultrasound.Preheating is preferably done to a temperature of from about 50° C. toabout 100° C.

Other operating conditions in the ultrasound chamber can vary as well,depending on the material being treated and the throughput rate. The pHof the emulsion, for example, may range from as low as 1 to as high as10, although best results are generally achieved within a pH range of 2to 7. The pressure of the emulsion as it is exposed to ultrasound canlikewise vary, ranging from subatmospheric (as low as 5 psia or 0.34atmosphere) to as high as 3,000 psia (214 atmospheres), althoughpreferably less than about 400 psia (27 atmospheres), and morepreferably less than about 50 psia (3.4 atmospheres), and mostpreferably from about atmospheric pressure to about 50 psia.

An advantage of the present invention is that the process and equipmentcan treat fossil fuels, petroleum fractions, and other materials at ahigh throughput rate. Preferred throughput rates of the oil phase arefrom about 5 to about 500 gallons (U.S.) per minute (about 0.3 to about30 L/sec), and most preferred are from about 8 to about 160 gallons(U.S.) per minute (about 0.5 to about 10 L/sec).

The foregoing is offered primarily for purposes of illustration. Furthervariations in the components of the apparatus and system, theirarrangement, the materials used, the operating conditions, and otherfeatures disclosed herein that are still within the scope of theinvention will be readily apparent to those skilled in the art.

1. A flow-through reactor for the continuous treatment of a liquidmaterial with ultrasound, said flow-through reactor comprising: areaction vessel, an elongate ultrasonic horn having first and secondopposing end surfaces, said ultrasonic horn mounted to said reactionvessel with said first end surface extending into the interior of saidreaction vessel, an electrical power source, an ultrasonic transduceroperatively connecting said electrical power source to said second endsurface of said ultrasonic horn to convert said electrical energy fromsaid electrical power source to ultrasonic vibrations in said ultrasonichorn, and entry and exit ports in said reaction vessel arranged to causeliquid material entering said reaction vessel to strike said first endsurface and flow across said first end surface before leaving saidvessel through said exit port.
 2. The flow-through reactor of claim 1wherein said elongate ultrasonic horn further comprises a side surfacejoining said first and second end surfaces, said ultrasonic horn ismounted to said reaction vessel with said first end surface and at leasta portion of said side surface extending into the interior of saidreaction vessel, and said exit port is arranged to cause said liquidmaterial to flow along said portion of said side surface before leavingsaid vessel through said exit port.
 3. The flow-through reactor of claim1 wherein said entry port is positioned less than 3.0 cm from said firstend surface of said ultrasonic horn.
 4. The flow-through reactor ofclaim 1 wherein said entry port is positioned less than 2.0 cm from saidfirst end surface of said ultrasonic horn.
 5. The flow-through reactorof claim 1 wherein said reaction vessel has an internal wall surfacethat is complementary in contour to side surface of said ultrasonic hornwith a clearance of less than 2.0 cm between said internal wall surfaceand said side surface.
 6. The flow-through reactor of claim 5 whereinsaid clearance is less than 1.5 cm.
 7. The flow-through reactor of claim5 wherein said clearance is less than 1.0 cm.
 8. Apparatus forgenerating ultrasonic vibration, said apparatus comprising: anultrasonic horn, an ultrasonic transducer arranged to receive electricalenergy and to convert said electrical energy to ultrasonic vibrations,and a vibration transmitting block joining said ultrasonic transducer tosaid ultrasonic horn to transmit said ultrasonic vibrations from saidultrasonic transducer to said ultrasonic horn, in which at least one ofsaid ultrasonic horn and said vibration transmitting block is clad withan ultrasound reflecting cladding.
 9. The apparatus of claim 8 whereinsaid vibration transmitting block is shaped to amplify said ultrasonicvibrations and is clad with an ultrasound reflecting cladding.
 10. Theapparatus of claim 8 wherein said vibration transmitting block iscomprised of a first metal selected from the group consisting of steel,nickel, aluminum, titanium, copper, and alloys of nickel, aluminum,titanium and copper, and said cladding is comprised of a second metaldifferent from said first metal and selected from the group consistingof silver, gold, copper and aluminum.
 11. The apparatus of claim 8wherein said cladding is on said vibration transmitting block and issilver.
 12. The apparatus of claim 8 wherein said vibration transmittingblock is comprised of steel and said cladding is a member selected fromthe group consisting of silver, gold, copper and aluminum.
 13. Theapparatus of claim 8 wherein said vibration transmitting block iscomprised of steel and said cladding is a member selected from the groupconsisting of silver and gold.
 14. The apparatus of claim 8 wherein saidvibration transmitting block is comprised of steel and said cladding issilver.
 15. A flow-through reactor for the continuous treatment of aliquid material with ultrasound, said flow-through reactor comprising: areaction vessel, an elongate ultrasonic horn having first and secondopposing end surfaces joined by a side surface, said ultrasonic hornmounted to said reaction vessel with said first end surface and at leasta portion of said side surface extending into the interior of saidreaction vessel, an electrical power source, an ultrasonic transduceroperatively connecting said electrical power source to said second endsurface of said ultrasonic horn to convert said electrical energy fromsaid electrical power source to ultrasonic vibrations in said ultrasonichorn, a vibration transmitting block joining said ultrasonic transducerto said ultrasonic horn to transmit said ultrasonic vibrations from saidultrasonic transducer to said ultrasonic horn, said vibrationtransmitting block clad with an ultrasound reflecting cladding, andentry and exit ports in said reaction vessel arranged to cause liquidmaterial entering said reaction vessel to strike said first end surfaceand flow across said first end surface before leaving said vesselthrough said exit port.
 16. The flow-through reactor of claim 15 whereinsaid vibration transmitting block is comprised of steel and saidcladding is a member selected from the group consisting of silver andgold.
 17. The flow-through reactor of claim 15 wherein said cladding ison said vibration transmitting block and is silver.
 18. The flow-throughreactor of claim 15 wherein said vibration transmitting block iscomprised of steel and said cladding is silver.
 19. A process fortreating a liquid fossil fuel by ultrasound, said process comprisingcontinuously passing a fluid comprising said liquid fossil fuel andwater through a reactor comprising: a reaction vessel, an elongateultrasonic horn having first and second opposing end surfaces, saidultrasonic horn mounted to said reaction vessel with said first endsurface extending into the interior of said reaction vessel, and anultrasonic transducer that converts electrical energy to ultrasonicvibrations, said ultrasonic transducer operatively connecting anelectrical power source to said second end surface of said ultrasonichorn to transmit ultrasonic vibrations through said ultrasonic horn tosaid first end surface, while supplying electrical energy to saidultrasonic transducer to produce said ultrasonic vibrations at saidfirst end, and causing said fluid upon entering said reaction vessel tofirst strike said first end surface of said ultrasonic horn in adirection substantially normal to said first end surface and then toflow across said first end surface.
 20. The process of claim 19 furthercomprising feeding said fluid to said reaction vessel through an entryport in said reaction vessel that is positioned less than 3.0 cm fromsaid first end surface of said ultrasonic horn.
 21. The process of claim19 further comprising feeding said fluid to said reaction vessel throughan entry port in said reaction vessel that is positioned less than 2.0cm from said first end surface of said ultrasonic horn.
 22. The processof claim 19 further comprising feeding said fluid to said reactionvessel through an entry port in said reaction vessel that is positionedless than 1.5 cm from said first end surface of said ultrasonic horn.23. The process of claim 19 comprising continuously passing said fluidthrough said reactor at a rate that includes a fossil fuel flow rate offrom about 0.3 to about 30 L/sec.
 24. The process of claim 19 comprisingcontinuously passing said fluid through said reactor at a rate thatincludes a fossil fuel flow rate of from about 0.5 to about 10 L/sec.25. The process of claim 19 further comprising feeding said fluid tosaid reaction vessel through an entry port in said reaction vessel thatis positioned less than 1.5 cm from said first end surface of saidultrasonic horn, at a rate that includes a fossil fuel flow rate of fromabout 0.5 to about 10 L/sec.
 26. The process of claim 19 wherein saidfluid is an emulsion consisting of an aqueous phase and an organic phasein which said aqueous phase constitutes from about 20% to about 75% byvolume of said emulsion.
 27. The process of claim 19 wherein said fluidis an emulsion consisting of an aqueous phase and an organic phase inwhich said aqueous phase constitutes from about 30% to about 50% byvolume of said emulsion.
 28. The process of claim 19 wherein saidelectrical energy is at a wattage of from about 1 to about 10 kilowatts.29. The process of claim 19 wherein said electrical energy is in theform of a pulsewise voltage at a frequency of from about 10 to about 50megahertz and a wattage of about 1 to about 10 kilowatts.
 30. Theprocess of claim 19 wherein said ultrasonic transducer is operativelyconnected to said ultrasonic horn through a vibration transmitting blockthat is clad with an ultrasound reflecting cladding.
 31. The process ofclaim 30 wherein said vibration transmitting block is comprised of afirst metal selected from the group consisting of steel, nickel,aluminum, titanium, copper, and alloys of nickel, aluminum, titanium,and copper, and said cladding is comprised of a second metal differentfrom said first metal and selected from the group consisting of silver,gold, copper and aluminum.
 32. The process of claim 30 wherein saidvibration transmitting block is comprised of steel and said cladding isa member selected from the group consisting of solver, gold, copper andaluminum.
 33. The process of claim 30 wherein said vibrationtransmitting block is comprised of steel and said cladding is silver.